Storage system

ABSTRACT

According to one embodiment, a storage system includes storage devices configured to execute communication by using an identifier, a converter configured to convert the identifier of the storage devices, a controller configured to execute communication with the storage devices via the converter by using the identifier converted by the converter, convert a DC power output from the storage devices into a DC power of a predetermined magnitude and output the DC power, and charge the storage devices with the DC power of the predetermined magnitude, an AC/DC converter configured to convert the DC power output from the controller into an AC power, convert an AC power supplied from a distribution system into a DC power and supply the DC power to the controller, and a controller configured to control the controller and the AC/DC converter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2011-166778, filed Jul. 29, 2011,the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a storage system.

BACKGROUND

Recently, vehicles such as an electronic vehicle (EV) having a motordriven by an electric power supplied from a battery have spread. Theelectric vehicle comprises a storage device which comprises both thebattery and a battery management unit (BMU) configured to controlcharging and discharging of the battery. The battery management unitexchanges control information with an electronic control unit (ECU) ofthe electric vehicle by a control area network (CAN) communicationprotocol. The CAN communication protocol identifies communicationinformation by a unique identifier called CANID, in the communicationarea. The BMU therefore executes communication using a unique identifierin the communication area of the electric vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a configuration example of a storage systemof a first embodiment;

FIG. 2 schematically shows a configuration example of a storage systemof a second embodiment;

FIG. 3 shows a configuration example of a CAN gateway in the storagesystem shown in FIG. 2;

FIG. 4 schematically shows a configuration example of a storage systemof a third embodiment;

FIG. 5 shows a configuration example of a CAN gateway in the storagesystem shown in FIG. 4;

FIG. 6 schematically shows a configuration example of a storage systemof a fourth embodiment; and

FIG. 7 shows a configuration example of a CAN gateway in the storagesystem shown in FIG. 6.

DETAILED DESCRIPTION

In general, according to one embodiment, a storage system includes aplurality of storage devices configured to execute communication byusing an identifier; a converter configured to convert the identifier ofthe plurality of storage devices; a charge/discharge controllerconfigured to execute communication with the plurality of storagedevices via the converter by using the identifier converted by theconverter, convert a DC power output from the plurality of storagedevices into a DC power of a predetermined magnitude and output the DCpower, and charge the storage devices with the DC power of thepredetermined magnitude; an AC/DC converter configured to convert the DCpower output from the charge/discharge controller into an AC power,convert an AC power supplied from a distribution system into a DC powerand supply the DC power to the charge/discharge controller; and acontroller configured to control the charge/discharge controller and theAC/DC converter.

A storage system of embodiments will be described below with referenceto the accompanying drawings.

FIG. 1 schematically shows a configuration example of a storage systemof a first embodiment. The storage system of the present embodimentcomprises a plurality of storage devices 10A, 10B and 10C, a CAN gateway20 serving as a converter, a charge/discharge controller 30, an AC/DCconverter 40, and a controller 50.

First, a power system of the storage system of the present embodimentwill be described.

Each of the plurality of storage devices 10A, 102 and 10C comprises anassembled battery BT containing a plurality of battery cells, and abattery management unit 12. The storage devices 10A, 10B and 10C arereused batteries which have been used on electric vehicles of the sametype.

In the present embodiment, the battery cells of the assembled battery BTare lithium-ion batteries. The battery cells are not limited tolithium-ion batteries, but may be other batteries such asnickel-hydrogen batteries, lead batteries and nickel-cadmium batteries.

The battery management unit 12 monitors temperature and voltage of thebattery cells, equalizes charge amounts of the battery cells, andcontrols charging and discharging of the assembled battery BT.

The battery management unit 12 executes communications by using a CANcommunication protocol.

The charge/discharge controller 30 is a DC/DC converter which comprisesa PWM (pulse width modulation) controllable switching device, and whichreceives a DC power from each of the plurality of storage devices 10A,10B and 10C, converts the DC power into a DC power of a predeterminedmagnitude, and outputs the DC power to a DC load 70 or receives a DCpower output from the AC/DC converter 40, converts the DC power into aDC power of a predetermined magnitude, and outputs the DC power to thestorage devices 10A, 10B and 10C.

For example, a DC power of 200-300V is mutually transmitted between thestorage devices 10A, 10B and 10C, and the charge/discharge controller30, and a DC power of 350V-400V is mutually transmitted between thecharge/discharge controller 30 and AC/DC converter 40.

The AC/DC converter 40 is a bidirectional converter, which is connectedto a distribution system, an AC load 60, the charge/discharge controller30, and the DC load 70. The AC/DC converter 40 comprises a PWMcontrollable switching device, and converts the AC power supplied fromthe distribution system into the DC power and outputs the DC power tothe charge/discharge controller 30 or DC load 70, or converts the DCpower output from the charge/discharge controller 30 into the AC powerand outputs the AC power to the distribution system and AC load 60. Forexample, the AC power of 200V-220V is mutually transmitted between thedistribution system and the AC/DC converter 40.

Next, a communication system in the storage system of the presentembodiment will be described.

The storage system of the present embodiment communicates with theoutside by Ethernet(R), and communication is executed inside the storagesystem by the CAN communication protocol.

The controller 50 transmits a control signal to the charge/dischargecontroller 30 and the AC/DC converter 40, in accordance with a controlsignal from a host system 80. The controller 50 communicates with thehost system 80 by Ethernet(R), and communicates with thecharge/discharge controller 30 and the AC/DC converter 40 by the CANcommunication protocol.

The CAN gateway 20 converts CANID (identifier) used when the storagedevices 10A, 10B and 10C communicate by the CAN communication protocolinto a CANID which can be identified by the charge/discharge controller30.

The CAN gateway 20 may use, for example, an identifier notified by thecharge/discharge controller 30 or controller 50 as the CANID of thestorage devices 10A, 10B and 10C, or may use an identifier according toa position of a hardware configuration to which the storage devices 10A,10B and 10C are attached as the CANID of the storage devices 10A, 10Band 10C. The CAN gateway 20 may create an identifier by using a numberassigned to the charge/discharge controller 30 to which the storagedevices 10A, 10B and 10C are connected and numbers assigned sequentiallyto the plurality of storage devices connected to the charge/dischargecontroller 30.

Thus, even if the CANIDs used in the plurality of storage devices 10A,10B and 10C are duplicated, the charge/discharge controller 30 cancommunicate with the plurality of storage devices 10A, 10B and 10C viathe CAN gateway 20.

The charge/discharge controller 30 communicates with the plurality ofstorage devices 10A, 10B and 10C via the CAN gateway 20. For example, ifthe overcharge or overdischarge of the battery cell is notified, thecharge/discharge controller 30 notifies the controller of theabnormality and protects the storage devices by suspension of charging,suspension of discharging, etc.

Since the charge/discharge controller 30 and the plurality of storagedevices 10A, 10B and 10C communicate with each other via the CAN gateway20 as described above, the charge/discharge controller corresponding toeach of the plurality of storage devices 10A, 10B and 10C does not needto be provided. Even if the reused battery is incorporated in thestorage system, increase in costs for the storage system can beprevented.

The storage device carried on a vehicle such as the electric vehicle isexchanged with a new storage device when a storage capacity of thebattery is smaller than a predetermined amount. The storage device usedon the electric vehicle cannot be used as a power supply of the electricvehicle, but can be used for the other purposes.

It is expected that a number of used storage devices reducing the valueof use as the power supplies of the electric vehicles will appear infuture as spreading of the electric vehicles. Thus, reuse of the usedstorage devices has been desired.

When the used storage devices are to be reused, it is desirable to usethe batteries and battery management units as they are. However, if thestorage system was constituted by combining the battery management unitswhich have executed communication under the CAN communication protocolon a plurality of electric vehicles of the same type, CANIDs forexchanging the control information were duplicated and the control wasunable to be executed by a common battery charge/discharge controller.If a charge/discharge controller was provided for one storage device,reduction of the costs for the storage system was difficult.

In addition, the communication rates of the battery management unitswere often varied, based on difference in the type of the storagedevices. In this case, the control signal was unable to be communicatedby the CAN communication protocol.

In other words, according to the storage system of the presentembodiment, a cheap storage system allowing the used storage devices tobe mounted can be provided.

Next, a storage system of the second embodiment will be described belowwith reference to the drawings. In the following descriptions, the sameconstituent elements as those in the first embodiment are denoted withthe same reference numbers and their explanations are omitted.

FIG. 2 schematically shows a configuration example of the storage systemof the present embodiment. The storage system of the present embodimentis different in configuration of communication system from theabove-described first embodiment. The storage system of the presentembodiment comprises the same number of CAN gateways 20A, 20B and 20C asa plurality of storage devices 10A, 10B and 10C. The storage system ofthe present embodiment comprises the same configuration as the storagesystem of the first embodiment except the configuration of the CANgateways 20A, 20B and 20C.

FIG. 3 shows a configuration example of the CAN gateways 20A, 20B and20C in the storage system of the present embodiment. Each of the CANgateways 20A, 20B and 20C comprises an identifier converter 21 androtary switches 20A and 20B. In FIG. 3, all of CANIDs which theplurality of storage devices 10A, 10B and 10C use for communication are“0x7FF” and are duplicated.

An identifier converter 21 converts a CANID used in each of the storagedevices 10A, 10B and 10C with a

DC/DC number and a connection number provided by a charge/dischargecontroller 30, and a first expansion ID and a second expansion ID set ineach of the storage devices 10A, 10B and 10C.

The DC/DC number provided by the charge/discharge controller 30 is thenumber assigned to the charge/discharge controller 30 to which thestorage devices 10A, 10B and 10C are connected. Since the storage systemof the present embodiment comprises the single charge/dischargecontroller 30, a common DC/DC number “1” is provided to the storagedevices 10A, 10B and 10C.

The connection number provided by the charge/discharge controller 30 isthe number assigned sequentially to each of the storage devices 10A, 10Band 10C connected to the single charge/discharge controller 30. In thepresent embodiment, a connection number of the storage device 10A is“1”, a connection number of the storage device 10B is “2”, and aconnection number of the storage device 10C is “3”.

Each of the CAN gateways 20A, 20B and 20C comprises two rotary switchesSW1 and SW2 to which numbers corresponding to positions of knobs areassigned. The first expansion ID and the second expansion ID are set byoperating the rotary switches SW1 and SW2. In the present embodiment,the first expansion ID of the storage device 10A is “1” and the secondexpansion ID thereof is “1”, the first expansion ID of the storagedevice 10B is “1” and the second expansion ID thereof is “2”, and thefirst expansion ID of the storage device 10C is “1” and the secondexpansion ID thereof is “3”.

The identifier converter 21 converts the CANID of each of the storagedevices 10A, 10B and 10C, with the DC/DC number, the connection number,the first expansion ID, and the second expansion ID. In other words,numbers of four digits are added in order of the DC/DC number, theconnection number, the first expansion ID and the second expansion ID,to the end of original CANID “0x7FF” of each of the storage devices 10A,10B and 10C, to form a new CANID. More specifically, an expansion ID ofexpansion format 18bit in the CAN data frame, etc. are utilized.

The CAN gateway 20A adds “1111” to the end of the original CANID “0x7FF”of the storage device 10A to form a CANID “0x7FF1111” upon executingcommunication from the storage device 10A to the charge/dischargecontroller 30, and removes the numbers of four digits at the end of theCANID “0x7FF1111” to form the CANID “0x7FF” upon executing communicationfrom charge/discharge controller 30 to the storage device 10A.

The CAN gateway 20B adds “1212” to the end of the original CANID “0x7FF”of the storage device 10B to form a CANID “0x7FF1212” upon executingcommunication from the storage device 10B to the charge/dischargecontroller 30, and removes the numbers of four digits at the end of theCANID “0x7FF1212” to form the CANID “0x7FF” upon executing communicationfrom charge/discharge controller 30 to the storage device 10A.

The CAN gateway 20C adds “1313” to the end of the original CANID “0x7FF”of the storage device 10C to form a CANID “0x7FF1313” upon executingcommunication from the storage device 10C to the charge/dischargecontroller 30, and removes the numbers of four digits at the end of theCANID “0x7FF1313” to form the CANID “0x7FF” upon executing communicationfrom charge/discharge controller 30 to the storage device 10C.

In the present embodiment, the identifier converter 21 converts theCANID by combining the numbers provided by the charge/dischargecontroller 30 with the numbers set in each of the CAN gateways 20A, 208and 20C, but may convert the CANID by the numbers provided by thecharge/discharge controller 30 alone or by the numbers set in each ofthe CAN gateways 20A, 20B and 20C alone.

Since the charge/discharge controller 30 and the plurality of storagedevices 10A, 10B and 10C communicate with each other via the CANgateways 20A, 203 and 20C as described above, the charge/dischargecontroller corresponding to each of the plurality of storage devices10A, 10B and 10C does not need to be provided, similarly to theabove-described first embodiment. Even if the reused battery isincorporated in the storage system, increase in costs for the storagesystem can be prevented.

Furthermore, by connecting the CAN gateways 20A, 20B and 20C to theplurality of storage devices 10A, 10B and 10C, respectively, the CANgateways can be increased or decreased in accordance with the increaseor decrease of the storage devices incorporated in the storage system,and the size of the storage system can be easily changed.

In other words, according to the storage system of the presentembodiment, a cheap storage system allowing the used storage devices tobe mounted can be provided.

Next, a storage system of the third embodiment will be described belowwith reference to the drawings.

FIG. 4 schematically shows a configuration example of the storage systemof the present embodiment. The storage system of the present embodimentis different in configuration of communication system from theabove-described first embodiment. In the storage system of the presentembodiment, a plurality of storage devices 10A, 10B and 10C are thereused batteries which have been used on the electric vehicles ofdifferent types. Battery management units 12 of the storage devices 10Aand 10C communicate at the same speed as a communication speed (firstspeed) [bps] of the CAN communication in the storage system while thebattery management unit 12 of the storage device 10B communicates at acommunication speed (second speed) [bps] slower than the communicationspeed in the storage system.

The storage system of the present embodiment comprises CAN gateways 20A,20B and 20C as the same number of converters as the plurality of storagedevices 10A, 10B and 10C. The plurality of CAN gateways 20A, 20B and 20Care connected to a CAN communication bus line 100. A charge/dischargecontroller 30, an AC/DC converter 40, and a controller 50 are alsoconnected to a CAN communication bus line 100.

By connecting the CAN gateways 20A, 20B and 20C, the charge/dischargecontroller 30, and the controller 50 to the single CAN communication busline 100 as described above, information reference of the storagedevices 10A, 10B and 10C can be freely executed at the charge/dischargecontroller 30 and the controller 50.

The plurality of CAN gateways 20A, 20B and 20C convert the CANIDs usedby the storage devices 10A, 10B and 10C and, if there are storagedevices having different CAN communication speeds, allow thecommunication speeds to cooperate with each other.

FIG. 5 shows a configuration example of the CAN gateways 20A, 20B and20C in the storage system of the present embodiment. Each of the CANgateways 20A, 20B and 20C comprises an identifier converter 21, rotaryswitches SW1 and SW2, and communication speed setting switches SW3 andSW4.

The operations of the identifier converter 21 are the same as those inthe storage system of the above-described second embodiment. In otherwords, the identifier converter 21 converts the CANID used in each ofthe storage devices 10A, 10B and 10C with the DC/DC number and theconnection number provided by the charge/discharge controller 30, andthe first expansion ID and the second expansion ID set in each of theCAN gateways 20A, 20B and 20C.

The CAN gateway 20A adds “1111” to the end of the original CANID “0x7FF”of the storage device 10A to form a CANID “0x7FF1111” upon executingcommunication from the storage device 10A to the charge/dischargecontroller 30, and removes the four-digit number from the end of theCANID “0x7FF1111” to form the CANID “0x7FF” upon executing communicationfrom charge/discharge controller 30 to the storage device 10A.

The CAN gateway 20B adds “1212” to the end of the original CANID “0x7FF”of the storage device 10B to form a CANID “0x7FF1212” upon executingcommunication from the storage device 10B to the charge/dischargecontroller 30, and removes the four-digit number from the end of theCANID “0x7FF1212” to form the CANID “0x7FF” upon executing communicationfrom charge/discharge controller 30 to the storage device 10A.

The CAN gateway 20C adds “1313” to the end of the original CANID “0x7FF”of the storage device 10C to form a CANID “0x7FF1313” upon executingcommunication from the storage device 10C to the charge/dischargecontroller 30, and removes the four-digit number from the end of theCANID “0x7FF1313” to form the CANTO “0x7FF” upon executing communicationfrom charge/discharge controller 30 to the storage device 10C.

In addition, each of the CAN gateways 20A, 20B and 20C comprises thecommunication speed setting switch SW3 for setting the speed ofcommunication with the storage devices 10A, 108 and 10C and thecommunication speed setting switch SW4 for setting the speed ofcommunication with the charge/discharge controller 30 and the controller50. The communication speed setting switches SW3 and SW4 are dipswitches for changing the knobs to, for example, a Lo (second speed)side and a Hi (first speed) side.

In the present embodiment, since the communication speed (second speed)of the storage device 10B is different from the communication speed(first speed) in the storage system, the communication speed settingswitch SW3 is changed to the Lo side and the communication speed settingswitch SW4 is changed to the Hi side. In this case, the CAN gateway 20Bcommunicates with the storage device 10B at the second speed andcommunicates with the charge/discharge controller 30 and the controller50 at the first speed. For this reason, the communication speeds of thestorage devices incorporated in the storage system are not limited andvarious types of reused batteries can be mounted.

Since the charge/discharge controller 30 and the plurality of storagedevices 10A, 10B and 10C communicate with each other via the CANgateways 20A, 20B and 20C as described above, the charge/dischargecontroller corresponding to each of the plurality of storage devices10A, 103 and 10C does not need to be provided, similarly to theabove-described first embodiment. Even if the reused battery isincorporated in the storage system, increase in costs for the storagesystem can be prevented.

Furthermore, by connecting the CAN gateways 20A, 20B and 20C to theplurality of storage devices 10A, 10B and 10C, respectively, the CANgateways can be increased or decreased in accordance with the increaseor decrease of the storage devices incorporated in the storage system,and the size of the storage system can be easily changed, similarly tothe above-described second embodiment.

In the present embodiment, since each of the CAN gateways 20A, 20B and20C comprises the communication speed setting switches SW3 and SW4, thestorage device which executes communication at the communication speeddifferent from the communication speed in the storage system can also bemounted. If the communication speed in the storage system is constantand is not varied, the communication speed setting switch SW4 may beomitted.

In other words, according to the storage system of the presentembodiment, a cheap storage system allowing the used storage devices tobe mounted can be provided.

Next, a storage system of a fourth embodiment will be described belowwith reference to the drawings.

FIG. 6 schematically shows a configuration example of the storage systemof the present embodiment. The storage system of the present embodimentis different in configuration of communication system from theabove-described first embodiment. In the storage system of the presentembodiment, a plurality of storage devices 10A, 10B and 10C are reusedbatteries which have been used on electric vehicles of different types.Battery management units 12 of the storage devices 10A and 10Ccommunicate at a first speed (Hi-speed) while a battery management unit12 of the storage device 10B communicates at a second speed (Lo-speed).

The storage system of the present embodiment comprises the same numberof CAN gateways 20A, 20B and 20C as the plurality of storage devices10A, 10B and 10C, as converters, and further comprises a CAN gateway(second converter) 32 connected to a charge/discharge controller 30 anda CAN gateway (third converter) 42 connected to an AC/DC converter 40.

A plurality of CAN gateways 20A, 20B and 20C are connected to anEthernet communication line 200. The CAN gateways 32 and 42, and acontroller 50 are also connected to the Ethernet communication line 200.

The plurality of CAN gateways 20A, 20B and 20C communicate with thestorage devices 10A, 10B and 10C by using CANID and communicate with theCAN gateways 32 and 42, and a controller 50 by using IP addresses.

The CAN gateway 32 communicates with a charge/discharge controller 30 byusing the CANID and communicates with the CAN gateways 20A, 20B, 20C and42, and the controller 50 by using the IP addresses.

The CAN gateway 42 communicates with the AC/DC converter 40 by using theCANID and communicates with the CAN gateways 20A, 20B, 20C and 32, andthe controller 50 by using the IP addresses.

By connecting the CAN gateways 20A, 20B and 20C, the CAN gateways 32 and42, and the controller 50 to the single Ethernet communication line 200as described above, information reference of the storage devices 10A,10B and 10C can be freely executed at the charge/discharge controller 30and the controller 50. In addition, some or all parts of the CANgateways 20A, 20B, 20C, 32 and 42 can also be integrated. The CANgateways can also execute CAN communication with the storage devices10A, 10B and 10C and execute Ethernet communication with the controller50.

The storage system of the present embodiment also comprises connectionunits T1 and T2 which can be connected with other external devices. Theconnection units T1 and T2 are connected with the Ethernet communicationline 200. Devices which execute the Ethernet communication, for example,other DC power supply devices, data centers, communication terminals,etc. can be connected to the connection units T1 and T2. The devicesconnected to the connection units T1 and T2 can communicate with thecontroller 50 and the CAN gateways 20A, 208, 20C, 32 and 42 via theEthernet communication line 200.

If the storage devices are different in communication speed, theplurality of CAN gateways 20A, 20B and 20C allow the communicationspeeds to cooperate with each other.

FIG. 7 shows a configuration example of the CAN gateways 20A, 20B, 20C,32 and 42 in the storage system of the present embodiment. Each of theCAN gateways 20A, 20B and 20C comprises an Ethernet converter 22, rotaryswitches SW5 and SW6, and a communication speed setting switch SW3.

The Ethernet converter 22 creates an IP address to be used for theEthernet communication by using a network ID, a first host ID, and asecond host ID. In the present embodiment, the network ID in the storagesystem is “192.168.0”. The first host ID is set in accordance with aposition of a knob of the rotary switch SW5. The second host ID is setin accordance with a position of a knob of the rotary switch SW6.

The Ethernet converter 22 creates the IP address by adding numberscorresponding to the first host ID and the second host ID to the end ofthe network ID “192.168.0.”. In FIG. 7, the Ethernet converter 22creates the IP address of class C. It is desirable that the class of theIP address is selected in accordance with the size of the network.

For example, the Ethernet converter 22 of the CAN gateway 20A adds anumber “017” corresponding to the first host ID “1” and the second hostID “1” to the end of the network ID “192.168.0.” to create an IP address“192.168.0.017”. The CAN gateway 20A communicates with the storagedevice 10A by using a CANID “0x7FF” of the storage device 10A andexecutes communication via the Ethernet communication line 200 by usingthe created IP address “192.168.0.017”.

The Ethernet converter 22 of the CAN gateway 20B adds a number “018”corresponding to the first host ID “1” and the second host ID “2” to theend of the network ID “192.168.0.” to create an IP address“192.168.0.018”. The CAN gateway 20B communicates with the storagedevice 10B by using the CANID “0x7FF” of the storage device 10B andexecutes communication via the Ethernet communication line 200 by usingthe created IP address “192.168.0.018”.

The Ethernet converter 22 of the CAN gateway 20C adds a number “019”corresponding to the first host ID “1” and the second host ID “3” to theend of the network ID “192.168.0.” to create an IP address“192.168.0.019”. The CAN gateway 20C communicates with the storagedevice 10C by using the CANID “0x7FF” of the storage device 10C andexecutes communication via the Ethernet communication line 200 by usingthe created IP address “192.168.0.019”.

Each of the CAN gateways 32 and 42 also comprises the same configurationas the CAN gateways 20A, 20B and 20C, and creates IP addresses by usingthe network ID, the first host ID, and the second host ID though notshown in FIG. 7.

The CAN gateways 20A, 202 and 20C comprises the communication speedsetting switches SW3 for setting the speeds of communication with thestorage devices 10A, 10B and 10C, respectively. Each of thecommunication speed setting switches SW3 is a dip switch for changing aknob to, for example, a second speed (Lo) side or a first speed (Hi)side.

In the present embodiment, the communication speed of each of thestorage devices 10A and 10C is the first speed while the communicationspeed of the storage device 10B is the second speed. Therefore, thecommunication speed setting switch SW3 of each of the CAN gateways 20Aand 20B is changed to the Hi side, and the communication speed settingswitch SW3 of the CAN gateway 20C is changed to the Lo side. Thus, thecommunication speeds of the storage devices incorporated in the storagesystem are not limited, and various types of reused batteries can bemounted.

Since the charge/discharge controller 30 and the plurality of storagedevices 10A, 10B and 10C communicate with each other via the CANgateways 20A, 20B and 20C as described above, the devices can bespecified by the IP addresses. For this reason, a charge/dischargecontroller corresponding to each of the plurality of storage devices10A, 10B and 10C does not need to be provided. Even if the reusedbattery is incorporated in the storage system, increase in costs for thestorage system can be prevented.

Furthermore, since the Ethernet communication is executed by using theIP addresses in the storage system, the identifier can be selected in awider range as compared with the use of the CAID. In addition, accordingto the Ethernet communication, since the communication speeds can beenhanced and the communication band is wider as compared with the CANcommunication, more information elements can be communicated at a highspeed. By executing the Ethernet communication in the storage system,connection of the other devices to the connection units T1 and T2 toexpand the devices can be easily implemented and a more generalizedsystem can be provided.

By connecting the CAN gateways 20A, 202 and 20C to the plurality ofstorage devices 10A, 10B and 10C, respectively, the CAN gateways can beincreased or decreased in accordance with the increase or decrease ofthe storage devices incorporated in the storage system, and the size ofthe storage system can be easily changed, similarly to theabove-described second embodiment.

In the present embodiment, since each of the CAN gateways 20A, 20B and20C comprises the communication speed setting switch SW3, various typesof storage devices can be mounted.

In other words, according to the storage system of the presentembodiment, a cheap storage system allowing the used storage devices tobe mounted can be provided.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

1. A storage system comprising: a plurality of storage devicesconfigured to execute communication by using an identifier; a converterconfigured to convert the identifier of the plurality of storagedevices; a charge/discharge controller configured to executecommunication with the plurality of storage devices via the converter byusing the identifier converted by the converter, convert a DC poweroutput from the plurality of storage devices into a DC power of apredetermined magnitude and output the DC power, and charge the storagedevices with the DC power of the predetermined magnitude; an AC/DCconverter configured to convert the DC power output from thecharge/discharge controller into an AC power, convert an AC powersupplied from a distribution system into a DC power and supply the DCpower to the charge/discharge controller; and a controller configured tocontrol the charge/discharge controller and the AC/DC converter.
 2. Thestorage system of claim 1, wherein the converter converts the identifierby using number of the charge/discharge controller to which the storagedevices are connected, and numbers sequentially assigned to theplurality of storage devices connected to the charge/dischargecontroller.
 3. The storage system of claim 1, wherein the convertercomprises a rotary switch which sets number to be used upon convertingthe identifier.
 4. The storage system of claim 2, wherein the convertercomprises a rotary switch which sets number to be used upon convertingthe identifier.
 5. A storage system comprising: a plurality of storagedevices configured to execute communication at a predeterminedcommunication speed; a charge/discharge controller configured to converta DC power output from the plurality of storage devices into a DC powerof a predetermined magnitude and output the DC power, and charge thestorage devices with the DC power of the predetermined magnitude; anAC/DC converter configured to convert the DC power output from thecharge/discharge controller into an AC power, convert an AC powersupplied from a distribution system into a DC power and supply the DCpower to the charge/discharge controller; a controller configured tocontrol the charge/discharge controller and the AC/DC converter; and aconverter comprising a first communication speed setting meansconfigured to set a communication speed for communication with theplurality of storage devices, and intervening between the plurality ofstorage devices (10A-10C) and the charge/discharge controller.
 6. Thestorage system of claim 1, further comprising a communication bus lineto which the converter, the charge/discharge controller, and thecontroller are connected.
 7. The storage system of claim 5, furthercomprising a communication bus line to which the converter, thecharge/discharge controller, and the controller are connected.
 8. Thestorage system of claim 1, further comprising: an Ethernet communicationline to which the converter and the controller are connected; a secondconverter intervening between the charge/discharge controller and theEthernet communication line, configured to create an IP address of thecharge/discharge controller; a third converter intervening between theAC/DC converter and the Ethernet communication line, configured tocreate an IP address of the AC/DC converter; and connection unitsconfigured to make connection between the Ethernet communication lineand an external device, wherein the converter comprises Ethernetconverting means for creating an IP address of the storage devices. 9.The storage system of claim 2, further comprising: an Ethernetcommunication line to which the converter and the controller areconnected; a second converter intervening between the charge/dischargecontroller and the Ethernet communication line, configured to create anIP address of the charge/discharge controller; a third converterintervening between the AC/DC converter and the Ethernet communicationline, configured to create an IP address of the AC/DC converter; andconnection units configured to make connection between the Ethernetcommunication line and an external device, wherein the convertercomprises Ethernet converting means for creating an IP address of thestorage devices.
 10. The storage system of claim 3, further comprising:an Ethernet communication line to which the converter and the controllerare connected; a second converter intervening between thecharge/discharge controller and the Ethernet communication line,configured to create an IP address of the charge/discharge controller; athird converter intervening between the AC/DC converter and the Ethernetcommunication line, configured to create an IP address of the AC/DCconverter; and connection units configured to make connection betweenthe Ethernet communication line and an external device, wherein theconverter comprises Ethernet converting means for creating an IP addressof the storage devices.
 11. The storage system of claim 4, furthercomprising: an Ethernet communication line to which the converter andthe controller are connected; a second converter intervening between thecharge/discharge controller and the Ethernet communication line,configured to create an IP address of the charge/discharge controller; athird converter intervening between the AC/DC converter and the Ethernetcommunication line, configured to create an IP address of the AC/DCconverter; and connection units configured to make connection betweenthe Ethernet communication line and an external device, wherein theconverter comprises Ethernet converting means for creating an IP addressof the storage devices.
 12. The storage system of claim 5, furthercomprising: an Ethernet communication line to which the converter andthe controller are connected; a second converter intervening between thecharge/discharge controller and the Ethernet communication line,configured to create an IP address of the charge/discharge controller; athird converter intervening between the AC/DC converter and the Ethernetcommunication line, configured to create an IP address of the AC/DCconverter; and connection units configured to make connection betweenthe Ethernet communication line and an external device, wherein theconverter comprises Ethernet converting means for creating an IP addressof the storage devices.
 13. The storage system of claim 6, furthercomprising: an Ethernet communication line to which the converter andthe controller are connected; a second converter intervening between thecharge/discharge controller and the Ethernet communication line,configured to create an IP address of the charge/discharge controller; athird converter intervening between the AC/DC converter and the Ethernetcommunication line, configured to create an IP address of the AC/DCconverter; and connection units configured to make connection betweenthe Ethernet communication line and an external device, wherein theconverter comprises Ethernet converting means for creating an IP addressof the storage devices.
 14. The storage system of claim 7, furthercomprising: an Ethernet communication line to which the converter andthe controller are connected; a second converter intervening between thecharge/discharge controller and the Ethernet communication line,configured to create an IP address of the charge/discharge controller; athird converter intervening between the AC/DC converter and the Ethernetcommunication line, configured to create an IP address of the AC/DCconverter; and connection units configured to make connection betweenthe Ethernet communication line and an external device, wherein theconverter comprises Ethernet converting means for creating an IP addressof the storage devices.